U.S. patent application number 11/619281 was filed with the patent office on 2007-05-17 for guided power tool and method for operating a guided power tool.
Invention is credited to Dietmar Hahn, Erhard Hoffmann, Andreas Strasser.
Application Number | 20070107919 11/619281 |
Document ID | / |
Family ID | 35070458 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070107919 |
Kind Code |
A1 |
Strasser; Andreas ; et
al. |
May 17, 2007 |
GUIDED POWER TOOL AND METHOD FOR OPERATING A GUIDED POWER TOOL
Abstract
The present invention is based on a method for operating a
guided power tool (10), in particular an electric power tool, with
a rotatably and/or percussively driven insert tool (36), whereby
the insert tool (36) is driven into a work piece (34) in a work
process. It is proposed that at least one measured signal detected
at the power tool (10) during the work process is evaluated to
derive a property of the work piece (34) located in the working
direction of the Insert tool (36), and the power tool (10) is
operated in accordance with the property. A guided power tool is
also proposed.
Inventors: |
Strasser; Andreas;
(Rudersberg, DE) ; Hoffmann; Erhard; (Solothurn,
CH) ; Hahn; Dietmar; (Gerlingen, DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
35070458 |
Appl. No.: |
11/619281 |
Filed: |
January 3, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11103262 |
Apr 11, 2005 |
|
|
|
11619281 |
Jan 3, 2007 |
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Current U.S.
Class: |
173/1 ;
173/2 |
Current CPC
Class: |
B25F 5/00 20130101 |
Class at
Publication: |
173/001 ;
173/002 |
International
Class: |
B25B 21/02 20060101
B25B021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 2004 |
DE |
10 2004 017 939.5 |
Claims
1-11. (canceled)
12. A method for operating a guided power tool (10), comprising the
following steps: providing a rotatably and/or percussively driven
insert tool (36), whereby the insert tool (36) is adapted to be
driven into a work piece (34) in a work process; providing an
evaluation unit; evaluating at least one measured signal detected
at the power tool (10) during the work process with the evaluation
unit to derive a property of the work piece (34) located in the
working direction of the insert tool (36); and operating the power
tool (10) in accordance with the property.
13. The method as recited in claim 12, wherein detection and
evaluation are carried out repeatedly during the work process.
14. The method as recited in claim 12, wherein detection and
evaluation are carried out continuously during the work
process.
15. The method as recited in claim 12, wherein the power tool (10)
automatically adapts to the property of the work piece (34).
16. The method as recited in claim 12, wherein a warning signal is
output when a machining problem is detected.
17. The method as recited in claim 12, wherein at least one of the
signals is detected from the group composed of vibrations, sound,
torque, electric current and/or electrical voltage at the drive
motor (10), a rotational speed of the drive motor (12) and/or of
the insert tool (36).
18. The method as recited in claim 17, wherein two or more signals
are combined to derive the properties of the work piece (34).
19. The method as recited in claim 12, wherein the insert tool
produces a vibration signal, wherein the vibration signal of the
insert tool (36) is monitored and, when the vibration signal
changes, it is analyzed with regard for an embedded object located
in the working direction of the insert tool (36) and, when an
embedded object (38) is detected, the drive of the insert tool (36)
is adjusted and/or an alarm signal is output.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is based on a guided power tool and a
method for operating a guided power tool.
[0002] Hand-guided power tools, in particular electric power tools,
are used to drive an insert tool, e.g., a drill, in a work piece,
e.g., a wall, whereby the insert tool can be driven in a percussive
manner or a rotating manner with or without percussion. In this
process, the power tools do not take into account material,
structure-specific properties of the material, or foreign objects
such as pipes or cables that can be embedded in the material. If a
foreign object of this type is damaged by the insert tool, damage
can result and the operator can even be endangered.
[0003] Furthermore, position--finding devices are used--known
examples are metal detection devices, "stud finders" and universal
position-finding devices, for example--to locate objects such as
electrical lines or pipes embedded in the wall. For an operator of
a power tool it is complex and cumbersome, however, to investigate
a wall for the presence of embedded objects before drilling.
SUMMARY OF THE INVENTION
[0004] It is proposed that at least one measured signal detected at
the power tool during the work process is evaluated to derive a
property of the work piece located in the working direction of the
insert tool, and that the power tool is operated in accordance with
the property. A property of the work piece of this nature is its
internal composition, in particular. Accordingly, a "property of
the work piece" is understood to be a variable that is directly
detectable from the outside, preferably objects embedded in the
interior such as cables or pipes. A composition of the work piece
involving layers of different material having different hardnesses
is also preferably understood to be a property of the work piece.
Another preferably understood property of the work piece is the
fact that cavities or a potential opening are located in the work
piece, into which the insert tool could break through. "Working
direction" is understood to mean the direction in which machining
progress takes place, e.g., a drilling direction. The presence of
embedded objects, openings and the like results in machining
problems when an embedded object comes in contact with the insert
tool or the insert tool breaks through into an opening.
[0005] The method according to the present invention enables, in a
simple manner, the early detection of machining problems of this
type, in particular the detection of objects embedded in the work
piece, e.g., pipes or cables. Likewise, a change in the structure
of the work piece can be detected as work progresses, and the power
tool can adapt accordingly.
[0006] It is favorable to carry out detection and evaluation
repeatedly during the work process. It is particularly favorable to
carry out detection and evaluation permanently during the work
process. The continual monitoring of suitable measured signals by
an evaluation unit during the work process enables reliable
detection of the inner condition of the work piece. The information
obtained in this manner can be used to control or regulate the
power tool in an optimal manner or to provide an operator with
machining instructions or warning signals.
[0007] If the power tool automatically adapts to the property of
the work piece, damage to the work piece and/or an object embedded
in it, or the power tool itself, can be avoided. Furthermore,
operating comfort can be improved while good work progress is made.
If the intention is to drill through tiles attached to a wall, for
example, the first step can be to start drilling gently, without
percussion, using parameters suitable for tiles. If the evaluation
unit then detects masonry or stone as the main structure, the power
tool can then continue drilling using parameters that are suitable
for the material involved, e.g., with the highest impact force and
speed.
[0008] When a machining problem is detected, a warning signal can
be output. A machining problem of this type can be an upcoming
opening in the wall, for example, or an approach to an object
embedded in the work piece, such as a pipe. An evaluation unit can
detect the approach to an object of this type or an opening in the
wall using the detected measured signal itself and/or a change in
said measured signal. The evaluation unit preferably triggers a
motor electronics unit to turn the drive motor off and/or to output
a warning signal via a display unit. The display unit can output
acoustic and/or optical signals. If an opening in the wall is
encountered, the evaluation unit--once it detects the approach to
an opening--can output a warning signal via the display unit. As
the distance gets closer, the display unit can output a blinking
signal with increasing frequency or an acoustic signal that
increases in intensity, for example. The approach can be depicted
as a distance to the opening. Furthermore, the motor electronics
unit and a striking mechanism control, if present, can be
advantageously triggered to reduce their rotational and percussive
speed and/or the impact force, or to adapt them in a suitable
manner. The same procedure can be used when a pipe is
approached.
[0009] A measurement that provides useful information is possible
when, in a favorable embodiment, at least one signal from the group
composed of vibration, sound, torque, electric current and/or
electrical voltage at the drive motor, rotational speed of the
drive motor and/or of the insert tool, is detected. To derive the
properties of the work piece, two or more sensor signals are
preferably combined. Advantageously, suitable experiential values
are stored, e.g., in tables in the evaluation unit or in the motor
electronics unit, to correlate different combinations of detected
measured signals with material properties of the work piece that
may be present. If, during drilling in a wall, a drill comes close
to an embedded pipe, for example, a frequency and/or amplitude
signal from a vibration sensor that monitors the vibrations of the
drill changes, since the elastic voltage waves emitted by the drill
are reflected on the boundary of the object and interact with the
drill again. The evaluation unit can detect and evaluate this.
"Vibrations of the drill and/or insert tool" is understood to mean
a motion substantially perpendicular to or located at a larger
angle relative to the working direction. Likewise, sound
measurements, in particular structure-borne noise measurements, or
noise measurements can provide information about the interior
composition of the work piece.
[0010] In a preferred embodiment of the present invention, a
vibration signal of the insert tool is monitored and, if the
vibration signal changes, it is analyzed with regard for an
embedded object located in the working direction of the insert tool
and, if an embedded object is detected, the drive of the insert
tool is adjusted and/or an alarm signal is output. According to the
present invention, an embedded object such as a pipe or an
electrical line, or a potential opening are detected, for example,
before the insert tool comes in contact with it. The object can
then be allowed to continue approaching the object in a controlled
manner, or it can be halted altogether.
[0011] Furthermore, a guided power tool is proposed, with which an
insert tool is drivable by a drive motor located in a housing, and
with which an evaluation unit is provided with which the detected
sensor signals are capable of being evaluated to derive properties
of the work piece. The drive motor is preferably an electric motor.
Other types of drives are feasible, however, such as an internal
combustion engine or a pneumatic drive. Preferably, at least one
sensor is provided to detect at least one signal from the group
composed of vibration, sound, torque, electric current, rotational
speed. As an option, a striking mechanism control can be provided
for a striking mechanism, if provided. Preferably, a common drive
motor is provided for the insert tool and the striking mechanism.
As an option, separate drive units can also be provided. To
preferably prevent objects in a wall from being drilled or for the
preferable detection of openings in the wall, a striking mechanism
control is not mandatory, however, but it can be provided as an
option.
[0012] The present invention is suitable, in particular, for
drills, impact drills, drilling hammers, boring tools and the like.
Particularly favorable is the use of the method for the predictive
analysis and/or early detection of the impact of the insert tool
with the object embedded in the work piece, i.e., a "pre-impact
diagnosis" with a power tool.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Further embodiments, aspects and advantages of the present
invention also result from the exemplary embodiment of the present
invention shown below with reference to a drawing, independently of
their description in claims and without limitation of
generality.
[0014] The sole FIGURE below shows a preferred power tool in the
form of a hand-guided electric power tool.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] A preferred hand-guided power tool 10 is composed of a drive
motor 12 located in a housing 18, the drive motor driving an insert
tool 36 configured as a drill bit and retained in a detachable
manner in a tool holder 16, and is further composed of a motor
electronic unit 22 for controlling drive motor 12, and a striking
mechanism 14. In the exemplary embodiment, striking mechanism 14 is
equipped with a striking mechanism control 32, whereby striking
mechanism 14 is drivable by drive motor 12, so that insert tool 36
can be driven in a percussive or rotating manner, with or without
percussion. Separate drive units can also be provided for striking
mechanism 14 and insert tool 36. Drive motor 12 is supplied with
current via an electrical connecting cable 20. A rechargeable
operating means can also be provided, as an option. A speed sensor
26 is provided on drive motor 12 to detect the rotational speed of
drive motor 12.
[0016] With insert tool 36 configured as a drill, a hole 40 is
drilled in a work piece 34, which is a wall. An object 38 in the
form of an electrical line or a pipe is embedded in the wall; the
object can come in contact with insert tool 36 if work continues in
the working direction.
[0017] According to the present invention, a vibration sensor 28 is
provided on the end of power tool 10 facing insert tool 36. An
evaluation unit 24 is connected with motor electronics unit 22 via
signal lines. Motor electronics unit 22 receives signals from
rotational speed sensor 26. Evaluation unit 24 receives signals
from vibration sensor 28 and, as a function of these signals,
triggers a display unit 30 which, in the exemplary embodiment, is
an optical indicator lamp. Furthermore, evaluation unit 24 is
connected with striking mechanism control unit 32 via a signal
line. As an option, evaluation unit 24 can also be identical to
motor electronics unit 22.
[0018] If insert tool 36 approaches embedded object 38 in the
working direction during drilling in the wall, the amplitude and/or
frequency signal of the vibration signal changes in a
characteristic manner. Evaluation unit 24 detects the approach to
object 38 and triggers motor electronics unit 22, drive motor 12 to
turn off and/or it outputs a warning signal via display unit 30. As
an option, evaluation unit 24 can instead trigger striking
mechanism control 32 and motor electronics unit 22 to reduce the
rotational speed, percussive speed and/or impact force, and to
adapt to the situation in a suitable manner.
[0019] In addition to the vibration signal, sound measurements,
e.g., the evaluation of the noise or a structure-borne noise, can
be used; they react with sensitivity to the internal composition of
work piece 34. Furthermore, torque and/or rotational speed of drive
motor 12 and/or insert tool 36 and an electric current and/or
electrical voltage at drive motor 10 can also be used, and in
particular, their change when embedded object 38 is approached.
* * * * *